Azo dyestuffs



United States Patent AZO DYESTUFFS Hans Ruckstuhl, Otto Semi, and Walter Wehrli, Basel,

Switzerland, assignors to Sandoz A. G., Basel, Switzerland, a Swiss firm N0 Drawing. Application February 2 8, 1951,

I .Serial No. 213,303

Claims priority, application Switzerland 'March 2, 1950 6 Claims. (Cl. 260200) The present invention relates to new azo compounds which are in part useful dyestuffs themselves and which are endowed with a remarkable coupling energy whereby they are particularly useful for the production of new disazo and polyazo dyestuffs as a result of the ease with which they may be coupled with further diazo or diazoazo compounds, respectively.

The new azo compounds according to the present invention are prepared by substituting an OH group for the amino group in azo dyestuffs obtained by acid coupling and corresponding to the'formula wherein R2 has the previously-recited significance, with 2 amino -hydroxy-naphthalene-7-sulfonic acid or 1- amino-7-hydroxynaphthalene 3sulfonib acid or l-amino- -7hydroxynaphthalemi- L-sulfonie acid, and correspond respectively to the formulae The. substituents on the R2 tesidue'may vary widely and may, for example, be COOH, -COO.alkyl, -SO3H, -SO2NH2 as wellkasqalkyb, aralkyl-, arylor acyl-substituted sulf-amido groups, NOz, NHz as well as alky1-, aralkyl-,'arylor acyl-substituted amino groups, -0-alkyl, O-aralkyl, O-aryl, halogen, CN, CFa, N=N-aryl and other substit'uents.

The replacement of the amino group bythe hydroxyl group can, in neutral to caustic-alkaline medium, be carried out in a wide variety ofways. In some cases, simple heating of the aqueous solution of the dyestuff under 2 reflux sulfices to eifect the desired replacement; in other cases, heating for several hours to temperatures of, for instance, l40150 in an autoclave is necessary.

In acid medium, the aforesaid replacement can also 5 be realized in wide variety of ways. In some cases, heating for a brief period of time with dilute mineral acid is suflicient to achieve the replacement; in other cases, prolonged heating under reflux is required. A particularly smooth replacement is frequently realized by treatment 10 with nitrous acid at room temperature. In some cases,

concentrated mineral acid or organic acid, with or without the addition of nitrites, yields good results.

As previously indicated, the new derivatives of the present invention are themselves useful azo dyestulfs or, as a result of their remarkable coupling energy are very useful intermediates for the preparation of new disazo and polyazo dyestulls, including metallizable products which are particularly interesting.

The following examples further illustrate the invention Without, however, being limitative thereof. Parts and percentages are by weight; temperatures are in degrees centigrade.

EXAMPLE 1 503 parts of the sodium salt of the dyestutf, coupled in mineral acid solution, from diazobenzene-2,5-disulfonic acid and 2-amino-5whydroxynaphthalene-7-sulfonic acid are boiled under reflux for 4 hours in 2500 parts of water. The reaction product, which is in solution, with brown-red coloration, is salted outunder acid conditions and separated by filtration. It is a brown-red powder which dissolves in concentratedrsulfuric acid with bluish red coloration. It, corresponds to the formula SOaH 1 H033 OH OaH EXAMPLE 2 38.7 parts of the dyestufi obtained from l-diazobenzene-Z-carboxylic acid by acid coupling with Z-amino-S- hydroxynaphthalene7-sulfonic acid are heated for 8 hours to 140-150 with 1500 parts of 2.5% aqueous caustic soda solution in an autoclave. This operation results in complete replacement of the amino group by the hydroxyl group. The dyestutf, isolated by salting out and filtration, is a brown-red powder which dissolves in concentrated sulfuric acid with bluish red coloration. It corresponds to the formula HOaS OH It can be coupled for instance with the diazo compound of the disazo dyestutf corresponding to the formula A trisazo dyestutf results, the copper complex compound of which dyes cotton in grey shades.

EXAMPLE 3 45 parts of the dyestuif obtained from 2-diazo-1- methoxybenzene-4-sulfonic acid by acid coupling with 2-amino-5hydroxynaphthalene7-sulfonic acid are heated for 15 hours to 140-l50 with 1500 parts of 2.5% aqueous caustic soda solution in an autoclave whereby complete replacement of the amino group by the hydroxyl group takes place. The resultant dyestuff, isolated by salting out and filtration, is a dark powder which dissolved in concentrated sulfuric acid with blue-red coloration. It corresponds to the formula (|)CH3 i H035 -OH 50311 OH EXAMPLE 4 EXAMPLE 5 46.7 parts of the dyestufi obtained from l-carboxy-Z- diazobenzene-4-sulfonic acid and 1-amino-7-hydroxynaphthalene-3-sulfonic acid in acetic acid solution are heated for 2 hours to 140-150 in 500 parts of 2% aqueous caustic soda solution. The dyestuli separated by salting out and filtration, is a red powder which dissolves in water with reddish coloration and in concentrated sulfuric acid with brown-red coloration. It corresponds to the formula SOsH SOBH

EXAMPLE 6 43.2 parts of the dyestuff obtained from 5-nitro-2- diazobenzene-lcarboxylic acid by acid coupling with 2- amino-S-hydroxynaphthalene 7 sulfonic acid are dissolved neutral in 700 parts of water with the calculated amount of aqueous caustic soda solution. The solution is boiled under reflux for 48 hours with 35 parts of con centrated hydrochloric acid. The amino group is thereupon completely replaced by the hydroxyl group. The new dyestuff, corresponding to the formula SOaH is isolated by direct filtration and is converted into the sodium salt which, in dried state, is a dark brown powder which dissolves in concentrated sulfuric acid with reddish blue coloration.

It can easily be coupled with f. i. the intermediate obtained by alkaline coupling 2 mols of tetrazotized 3.3- dimethoxy-4.4'-diamino-diphenyl with 1 mol of the sodium salt of l-hydroxynaphthalene-3.8-disulfonic acid; a trisazo dyestuif is obtained, the copper complex compound of which dyes cotton in navy blue shades of good fastness properties.

The dyestutf obtained from 4-nitro-2-diazobenzene-1- carboxylic acid by acid coupling with 2-amino-5-hydroxynaphthalene-7-sulfonic acid is converted, by proceeding precisely analogously to the description set forth in the preceding paragraph, into the corresponding dihydroxynaphthalene sulfonic acid dyestufi of the formula C O OH HO S EXAMPLE 7 46.7 parts of the dyestuff obtained from l-carboxy-Z- diazobenzene-4-sulfonic acid by acid coupling with 2- amino-5hydroxynaphthalene-7sulfonic acid are boiled under reflux for 2 hours in 700 parts of water to which 35 parts of concentrated hydrochloric acid have been addled. The new dyestuff, which corresponds to the formu a GOOH H0 8 OH 803E is isolated by salting out and filtration. Dried, it is a brown-red powder which dissolves in concentrated sulfuric acid with reddish blue coloration.

If it is coupled in an alkaline medium with l-diazo-2- methoxy-4-nitrobenzene and the so-obtained disazo dyestulf condensed by glucose, an azoxy dyestuif of great value results which possesses the formula I H038 OH O O OH The copper complex compound of this azoxy dyestuff dyes cotton in bluish grey shades of good fastness properties.

EXAMPLE 8 46.7 parts of the dyestuff obtained from l-carboxy2- diazobenzene-S-sulfonic acid by acid coupling with 2- amino-5hydroxynaphthalene-7-sulfonic acid are boiled under reflux for 4 hours in 500 parts of water containing 30 parts of concentrated hydrochloric acid. The new dyestuff is precipitated with salt and is isolated by filtration. In dried state, it is a red-brown powder which dissolves in concentrated sulfuric acid with reddish blue coloration. It corresponds to the formula (IJOOH EXAMPLE 9 57.1 parts of the dyestutf obtained from 3-carboxy-4- diazo-l,1azobenzene-4-sulfonic acid by acid coupling with 2-amino-5-hydroxy-naphthalenefl sulfionic acid are dissolved neutral in 1000 parts of water with the calculated quantity of aqueous caustic soda solution. The solution is boiled under reflux for 3 hours with 60 parts of concentrated hydrochloric acid, and the formed acidsensitive dihydroxynaphthalene sulfonic acid dyestulf of the formula 57.1 parts of the dyestulf obtainedfrom 3'-carboxy-4- diazo-l,1-azobenzene-4-sulfonic acid by acid coupling with 2-amino-S-hydroxynaphthalene-7-sulfonic acid are dissolved in 2000 parts of water weakly alkaline with 14 parts of caustic soda. 6.9 parts of sodium nitrite are then added to the solution, and then the resultant mass is allowed to flow at 15 into a mixture of 60 parts of concentrated hydrochloric acid and 120 parts of water. The mixture is stirred for about 30 hours at room ternperature, whereupon the formed dyestuff is present wholly as the dihydroxynaphthalenesulfonic acid of the formula set forth in Example 9. The dyestutf, which is in part already present in crystalline form; is completely isolated by salting out hot, followed by filtration.

EXAMPLE ll is isolated by salting out. In dried state, it isa darkbrown powder which dissolves in concentrated sulfuric acid with reddish blue coloration.

. 6 The dyestufi obtained from Z-diazobenzene-lfi-dicarboxylic acid by acid coupling with 2-amino-5-hydroxynaphthalene-7-sulfonic acid is converted, according to the prescriptions of the preceding paragraph, into the cor responding dihydroxynaphthalenesulfonic acid dyestuff of the formula EXAMPLE 12 49.8 parts of the dyestutf obtained from 5.-nitro-2- diazo1:methoxy-benzene-4-sulfonic acid by acid coupling with 2-amino-5-hydroxynaphthalene-7-sulfonic acid are dissolved in 3000 parts of water made weakly alkaline with 10 parts of caustic soda, 6.9 parts of sodium nitrite added to the solution, and the resultant mixture allowed to flow at 15 into parts of 10% aqueous hydrochloric acid. After stirring the reaction mass for about 24 hours at room temperature, the new dyestufi of the formula is isolated. In dried state, it is a dark-brown powder which dissolves in concentrated sulfuric acid with reddish blue coloration.

OH COOH SOsH is salted out hot and is filtered. After being dried, it is a dark-brown powder which dissolves in concentrated sulfuric acid with cherry-red coloration.

EXAMPLE 14 46.7 parts of the dyestuif obtained from l-carboxy-2 diazobenzenel-sulfonic acid by acid coupling with lamino-7 hydroxynaphthalene-3-sulfonic acid aredissolved in 1400 parts of boiling water, and the solutionrendered acid by the dropwise addition of 50 parts ofccncentrated hydrochloric acid. After boiling for a short time, the formed precipitate goes completely into solution. The solution is rendered alkaline with caustic sodasolution and the dyestuff is precipitated with common salt. The dyestulf, after being isolated and dried, .is a red powder which dissolves in water with a red coloration and in concentrated sulfuric acid with a brown-red coloration.

It corresponds to the formula OH ('30 OH HO N=N -SO:H S03 EXAMPLE 15 45 parts of the dyestuff obtained by coupling 2-diazo- 1-methoxy benzene-4-sulfonic acid with 1-arnino-7-hydroxynaphthalene-3-sulfonic acid in acetic acid solution are dissolved in 1400 parts of water and after addition of 50 parts of concentrated hydrochloric acid are boiled under reflux for 12 hours. By isolation of the dyestuff as the sodium salt, it is obtained as a dark-brown powder which dissolves in water with yellow-red coloration and in concentrated sulfuric acid with blue-red coloration. The dyestuff corresponds to the formula (IJH (IJCHa HO N=N- -SO H 05H EXAMPLE 16 50.3 parts of the sodium salt of the dyestufl, coupled in strongly acetic acid solution, from diazobenzene-2,5- disulfonic acid and l-amino-7-hydroxynaphthalene-3-sulfonic acid are boiled under reflux for 2 to 3 hours in 1400 parts of water to which 50 parts of concentrated hydrochloric acid have been added, until complete dissolution has taken place. The dyestuff obtained by salting out is a dark powder which dissolves in water and in concentrated sulfuric acid with red-brown coloration. It corresponds to the formula SIOJH The following table sets forth, by way of further illustration of the invention, an additional number of examples in terms of the diazo and coupling components of the amino-dyestuffs and of the formulae of the c0rresponding dihydroxy-dyestutfs derived therefrom by proceeding according to the procedures set forth in the preceding examples; the color of the respective solutions in concentrated sulfuric acid before and after the replacement of the amino group by the hydroxy group is also indicated.

Table The formulae of the respective dihydroxynaphthalene sulfonic acid dyestuffs of the preceding table are:

racism-on n Hols -01;

l HOzsw-OH n 1 racism-0H Diazo Component Coupling Component Solution Color in Con. Sulfuric Acid l-amin obenzene 7-s1lf0nie aeid 1-aminobenzene-2-sulfonie acid. l-aminobenzene-ii-sulfon e med. 1 ammobenzene 2, 5 disuliome acid.

1 aminobenzene 2 carboxylic acid.

5-nitro-2-amino-l-methoxybenzene.

5 ehloro 2 aminobenzene l eerboxylic acid.

2amino-5-hydroxynaphthalene- NHrDyestutI CH-Dyestutl reddish blue bluish red.

yellowish green Do. bluish green Do. yellowish red Do.

bluish green Do.

blue reddish blue.

green reddish violet.

Having thus disclosed the invention what is claimed is: 1. A dyestufi derivative of the formula benzene series.

1 SOaH OCH 2. A dyestuif derivative of the formula I HOiS-@-OH 110111 3. A dyestufi derivative of the formula 4. A dyestuif derivative of the formula wherein R2 stands for a mononuclear aryl radical of the CODE H038 -OH 5. A dyestulf derivative of the formula III=N -N0a H018 -OH 6. A dyestufi derivative of the formula 1103s 0H 03H References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Zollinger: Helvetica Chemica Acta, vol. 23 (1950), No. 111, pg. 542. 

1. A DYESTUFF DERIVATIVE OF THE FORMULA 